Prostate cancer (PCa) is the second leading cause of cancer related deaths among males in the United States. Hispanic patients seem to have a lower five year relative survival rate regardless of the stage of disease than white non Hispanic. The long term goal is to identify new molecular markers related to progression of the disease. Current tumor markers in use in the clinical setting have been shown to have low specificity and low predictive value. New technologies for the analysis of the proteome and current technologies for the analysis of the genome of the prostate gland open a new window for identifying proteins and their genes that may selectively express during the early and late stages of prostate (PCa). Recently some studies have suggested distinct protein patterns expressed in the serum of Caucasian and African-American prostate cancer patients. No broad study has been done in a population with a strong Hispanic imheritance. We hypothesize that distinct proteome expression underlies the difference in stage progression and survival in the Hispanic population. In the proposed research a proteomics approach will be used in the examination of healthy and prostate cancer Hispanic patients in Puerto Rico. Our first aim is to establish protein patterns in the sera of these patients at the time of diagnosis and before any treatment. The methodology will incorporate the use of Surface Enhanced Laser Desorption Ionization (SELDI) to compare the patterns of protein expression in healthy patients and in newly diagnosed untreated PCa patients and compare them with published results for other ethnic populations. Protein patterns for 15 healthy and 20 PCa patients will be analyzed at baseline. Patterns found will be tested for their predictive value using an additional 25 blinded samples. Our second aim is the characterization of abundant protein species with altered expression in prostate cancer using gel proteolysis and protein sequencing and isoelectric focusing. In aim three we will correlate changes in protein patterns with stages of progression of the disease. Sera sample analysis will be performed through years 1-4 of this project to assay for changes in pattern that may correlate to progression. In the context of this project, results from these correlations may serve as the base for a broader study to find predictive markers to assign patients to specific therapies. This research will provide further understanding of the changes underlying the development of prostate cancer in Hispanics. This project will also provide the opportunity to increase the number of ethnic minority, trained clinical researchers and facilitate the recruitment of Hispanies into clinical research.